BulbSwitcherII.java

package math;


/**
 * Created by gouthamvidyapradhan on 08/09/2017.
 * There is a room with n lights which are turned on initially and 4 buttons on the wall.
 * After performing exactly m unknown operations towards buttons, you need to return how many different kinds of status of the n lights could be.
 * <p>
 * Suppose n lights are labeled as number [1, 2, 3 ..., n], function of these 4 buttons are given below:
 * <p>
 * Flip all the lights.
 * Flip lights with even numbers.
 * Flip lights with odd numbers.
 * Flip lights with (3k + 1) numbers, k = 0, 1, 2, ...
 * <p>
 * Example 1:
 * Input: n = 1, m = 1.
 * Output: 2
 * Explanation: Status can be: [on], [off]
 * <p>
 * Example 2:
 * Input: n = 2, m = 1.
 * Output: 3
 * Explanation: Status can be: [on, off], [off, on], [off, off]
 * <p>
 * Example 3:
 * Input: n = 3, m = 1.
 * Output: 4
 * Explanation: Status can be: [off, on, off], [on, off, on], [off, off, off], [off, on, on].
 * <p>
 * Note: n and m both fit in range [0, 1000].
 */
public class BulbSwitcherII {

    public static void main(String[] args) throws Exception {
        System.out.println(new BulbSwitcherII().flipLights(1, 1000));
    }

    public int flipLights(int n, int m) {
        if (n == 0 || m == 0) return 1;
        if (n == 1 && m >= 1) return 2;
        if (n == 2) {
            if (m == 1) return 3;
            if (m >= 2) return 4;
        } else if (n >= 3) {
            if (m == 1) return 4;
            if (m == 2) return 7;
        }
        return 8;
    }

}